1. Field of the Invention
This invention relates to an optical disc which enables recording of information such as a so-called CD-R or CD-RW, and also relates to an optical disc driving device.
2. Description of the Related Art
An optical disc is a disc-shaped recording medium having a signal recording layer such that recording and/or reproduction (hereinafter referred to as recording/reproduction) of information signals is carried out by casting a light beam onto the signal recording layer.
As such optical discs, reproduction-only optical discs such that pit arrays corresponding to information signals to be recorded are formed in advance on disc substrates, like CDs (compact discs) or CD-ROMs (CD-read only memories), have been popularly used. In such a reproduction-only optical disc, the major surface of the disc substrate on which pit arrays are formed has the function of the signal recording layer.
In the field of optical discs, additional writing and rewriting of information signals are strongly demanded. In such circumstances, for example, an optical disc which is used in a so-called compact disc recordable system and enables additional writing of information signals (hereinafter referred to as CD-R) is practically used. The signal recording layer of the CD-R on which information signals are recorded is made of an organic pigment-based material. By irradiating the signal recording layer with a light beam, the reflectance is changed at the irradiation position so as to carry out recording and the reflectance of the signal recording layer is detected to carry out reproduction of recorded signals.
As a recordable optical disc, a phase-changing optical disc like a CD-RW (CD-rewritable) which enables rewriting of recording signals by utilizing a phase change of the signal recording layer is practically used.
The above-described CD-R and CD-RW employ recording systems such as so-called disk at once, track at once, packet writing, and multi-session systems. In such cases, it is necessary to provide a program memory area (PMA) for temporarily storing address information necessary for continuous writing, in addition to a lead-in area and a lead-out area.
With such optical discs having a program memory area, it is demanded to securely discriminate the PMA and the lead-in area and carry out accurate reading operation. However, with the conventional CD-R and CD-RW, it is difficult to discriminate the subcode Q of the PMA and the subcode Q of the lead-in area on the basis of the data thereof.
Therefore, with these optical discs, identification between the PMA and the lead-in area is dependent solely on an ATIP (absolute time in pregroove) wobble signal. Therefore, there may be some inconvenience like malfunction and a long time required for discrimination.
In view of the foregoing status of the art, it is an object of the present invention to provide an optical disc which enables secure and instantaneous discrimination between the subcode Q of the PMA and the subcode Q of the lead-in area and which enables accurate reading of information in a short period of time, and to provide an optical disc driving device.
An optical disc according to the present invention comprises a data area in which information signals are recorded, a lead-in area and a lead-out area provided before and after the data area, and a program memory area for temporarily storing address information necessary for additionally writing information signals, wherein a subcode Q of the lead-in area and/or a subcode Q of the program memory area is provided with identification information for identifying the subcodes.
Also, an optical disc according to the present invention comprises a data area in which a wobbled track groove is formed and information signals are recorded, a lead-in area and a lead-out area provided before and after the data area, and a program memory area provided on the inner side than the lead-in area and adapted for temporarily storing address information necessary for additionally writing information signals, wherein a subcode Q of the lead-in area and/or a subcode Q of the program memory area is provided with identification information for identifying the subcodes.
An optical disc driving device according to the present invention is adapted for carrying out recording and/or reproduction of information signals by casting a light beam onto an optical disc comprising a data area in which information signals are recorded, a lead-in area and a lead-out area provided before and after the data area, and a program memory area for temporarily storing address information necessary for additionally writing information signals. The device comprises a data processing section for processing data obtained from a reflected light from the optical disc, wherein a subcode Q of the lead-in area and a subcode Q of the program memory area are discriminated on the basis of identification information provided for the subcode Q of the lead-in area and/or the subcode Q of the program memory area.